The singer tearfully addressed her mother's recent cancer battle while on stage in Glendale, Arizona, on Monday evening, as she paid tribute to the little boy that inspired her 2012 charity single, "Ronan."

Swift had been inspired by Ronan Thompson, a 4-year-old boy who died of cancer in 2011, after reading his mother's blog about Ronan's battle. During Monday's performance, Swift addressed Ronan's mother, Maya Thompson, who was in the audience.

"I wouldn't know half as much as I know about childhood cancer and childhood cancer research if she hadn't shared her story about her son Ronan," Swift told the crowd. "The thing about childhood cancer is that it's really, really hard to talk about. And it's really not something that you bring up...but the fact that she brought it up, she had this blog called Rockstar Ronan and I would read it every night. And in it was this account of what it was like to watch cancer take over my life."

"Since then, I've had cancer hit really close to me in my family," she said. "So because Maya's right there, I would like you to give her a round of applause, please. I just wanted to take a moment and try to play this song...I think because Maya's here tonight, I think she deserves it."

"I love you @taylorswift," she wrote. "You have my heart for the rest of my life and beyond." In another video of Swift's monologue, Thompson wrote: "I still can't believe you did this. This will forever be one of the most special moments of my life. Thank you @taylorswift for your beautiful heart and for never forgetting my Ro. I love you to the moon and back."

This isn't the first time Swift has shown compassion to those affected by cancer. This year alone, the singer donated $50,000 to a young fan battling the disease and granted a terminally ill 4-year-old's final wish.

"Usually when things happen to me, I process them and then write music about how I feel, and you hear it much later," she said in a Tumblr post in April. "This is something my family and I thought you should know about now."

The 25-year-old and her mother used the moment to encourage fans to ask their parents to engage in regular check-ups.

"Your parents may be too busy juggling everything they've got going on to go to the doctor, and maybe you reminding them to get checked for cancer could possibly lead to an early diagnosis and an easier battle," Swift wrote. "Or peace of mind in knowing that they're healthy and there's nothing to worry about. She wanted you to know why she may not be at as many shows this tour. She's got an important battle to fight."

Swift's performance on Monday was hardly the only heartfelt moment during her 1989 tour. Over the weekend, Swift delivered a sweet dedication to her new godson.